@pazznetwork/xmpp-adapter v1.0.0-beta

XMPP

General

Xmpp stands for "Extensible Messaging and Presence Protocol" and was called in the past Jabber, that is the reason why there are so many references to jabber instead of xmpp.

Xmpp connects over BOSH (Bidirectional-streams Over Synchronous HTTP) which means that 2 HTTP connection will be kept open which sends stanzas (XML payloads) to the server in the first and gets them in the second one. Xmpp can now be implemented with Websocket except secure reconnections, discovery and other specific technical expectations.

General Technical Design Guidelines

In general the xmpp design choices can be better understood if you imagine trying to make a chat out of email. Therefore, there a specifications for the case of multi-user clients on a device, multi device users, multi device users on multiple servers which all support or can support different sets of features while also the same client can offer the user multiple different sets of features to support.

The goal of the authentication as well the communication line encryption tries always to be as simple and secure as possible as-well as supporting all versions and iterations of the specifications dedicated to it.

As the clients struggled with a high amount of complexity for many users the complexity was pushed slowly back to the specifications also different specifications sets. Modern clients should orient themselves on the compliance for the XMPP IM (instant messaging) client and look for the extended protocols. See: https://xmpp.org/extensions/xep-0443.html#im and https://xmpp.org/extensions/xep-0369.html the MIX specification making it possible to skip the previous implementations.

TODO MORE:

Contact Management

Every user can write to any other user as long they know or have their jid, guessed of from a shared room. A user can be blocked or added to your contacts. An add to the contacts is a subscription to as users presence which will be broadcast by him when he logs in. When a user added you to your contacts you can also add them which creates a bidirectional subscriptions.

The add, remove and block are managed by the rooster spec and block spec which manage contact and block lists of a user.

There is always the case of the user writing without sending a contact request which leads to the need to also analyse the received messages by the user to visualize all contacts.

Messaging

In the core specification messages arrive to a user only when he is online and only to the specific client and specific device and are only kept in one session. For managing offline messages and the message history the Message Archive Management shorted to MAM was added.

When a server supports this feature

Other Message Features other Chat Clients offer and are in specification process:

• Time

Connection Management

To establish a stable connection the implementation of the ping specification is necessary to avoid timeouts if there are no actions performed on the connections. To have proper timeouts on requests there is the need for the ack specifications which checks regular if a set amount of requests was answered and makes a reconnections possible on the last set of packages.

Specifications

XMPP Core RFC-6121

XMPP Extension for Websocket RFC-7395

Extensible Messaging and Presence Protocol (XMPP): Instant Messaging and Presence

Abstract Specification extending or amending existing ones

XMPP Forms, XHTML, X-Forms

XEP-0004 Used in publish-subscribe, message-archive or multi-user-chat.

Extended Stanza Addressing

XEP-0033 Used to send one message to several JIDs at the same time and to forward messages.

Plugins

service-discovery

XEP-0030

plugin overview